Mapping the depths of the earth

March 2, 2012

As they drove through the Okavengo Delta in Botswana, a team of Woods Hole Oceano­graphic Insti­tute (WHOI) sci­en­tists and three North­easternphysics stu­dents encoun­tered a wild ele­phant attempting to pro­tect his home from the unlikely intruders.

Unde­terred, the team ven­tured on to obtain a singleGPS point along the East African Rift, which stretches between Kenya and Botswana and will even­tu­ally split the con­ti­nent in two.

“It’s the fastest-​​moving fault in the world, so if you under­stand how it evolves over time it can give you a sense of how slower-​​moving faults are evolving,” said Mathew Cham­ber­lain, who, along with fellow fourth-​​year stu­dents David Mar­golius and Colin Skinner, trav­eled to Africa and Hawaii to col­lect mag­ne­totel­luric data for their fall 2012co-​​op.

Mag­ne­totel­lurics (MT) is a method of deep-​​earth imaging that mea­sures vari­a­tions in the earth’s elec­tro­mag­netic field caused by solar energy. Based on the con­duc­tivity of the mate­rial under­ground, these mea­sure­ments help char­ac­terize what’s below, be it water, oil or lithosphere.

“We were using MT to image the fault in Botswana and Zambia, where the rifting is youngest. In Kenya, where the rift is older, you can lit­er­ally see the rocks ripped apart,” Mar­golius said.

While data col­lec­tion was the ulti­mate goal of the trip, gen­er­ating that data was a rather labo­rious task: The stu­dents worked 12-​​hour days under a hot sun, dig­ging trenches into which they deployed anMT data col­lector, 50-​​meter-​​long elec­trodes, coils that detect the mag­netic field and a car bat­tery to power the whole thing. A few days later, they’d return to dig it all up again.

After eight weeks in Africa, the stu­dents flew to Hawaii where they set out on a research vessel to col­lect MT data on the ocean floor of a remote part of the Pacific Ocean. In this case, the col­lected data would help WHOI esti­mate seismic activity across the globe.

Despite working and living along­side one another for six months, the stu­dents came away from the experiential-​​learning oppor­tu­nity with three dif­ferent goals for the future. Skinner said that working in Africa, where fre­quent black­outs made daily life dif­fi­cult, rein­forced the sig­nif­i­cance of the global energy crisis. “It has made me want to pursue research in new and extremely effi­cient renew­able energy sources,” he said.

Cham­ber­lain, on the other hand, is con­sid­ering a grad­uate edu­ca­tion in geo­physics – a field he only came to know during this co-​​op. Mar­golius found the hands-​​on aspect of field­work rewarding. “In the future, I’d like to be involved in research that cor­re­lates to more prac­tical appli­ca­tions,” he said.